TECHNICAL BULLETIN GENERAL INFORMATION NU-612 SMALL ANIMAL CAGE CHANGING STATION PERFORMANCE EVALUATION 2100 Fernbrook Lane Plymouth, MN 55447-4722 U.S.A. Phone: 763.553.1270 Fax: 763.553.0459 Toll Free: 1.800.328.3352 Background The NuAire Small Animal Cage Changing Station Model NU-612 is a station whose unique configuration offers the benefits of vertical HEPA filtered airflow for product protection on the worksurface. In addition, the NU-612 provides improved allergen personnel protection by incorporating a HEPA filtered down draft vacuum on the worktray to assure minimal exposure to animal hair/dander as well as cage bedding material. However, the NuAire Model NU-612 should not be used as a substitute for a Class II, Type A2 Biological Safety Cabinet. The NU-612 is not a containment device for airborne particulate in low to moderate risk-hazard research as prescribed by the CDC/NIH Biosafety in Microbiological and Biomedical Laboratories. As with all airflow devises, performance of the NU-612 is dependent upon the environment in which it is used. Activity in the room itself should be held to a minimum. Unnecessary activity may create disruptive air currents. A person walking past the station can cause draft velocities up to 250 fpm (1.27 m/s), which can interfere with the stations proper function. The NU-612's design and airflow pattern is illustrated on Drawing BCD-08610. The NU-612's design incorporates two impeller/blowers, both a supply and exhaust, each with its own associated HEPA filter providing excellent system function and maximum filter loading capacity. The designed airflow pattern, being a single pass system, also eliminates any heat build up within the workzone. The airflow pattern starts with the supply prefilter located on top of the station. The airflow continues through the supply impeller/blower and forced into the supply HEPA filter providing 99.99% particle removal at 0.3 micron. The airflow continues to move in a uniform vertical downflow pattern providing particulate-free air in the workzone. As the airflow continues to move toward the worktray, some particulate free downflow is pushed out the top two-thirds of the work access opening. The worktray configuration provides a unique downdraft airflow pattern that offers improved allergen personnel protection. Downdraft vacuum slots are provided around the worktray perimeter for improved particulate containment of animal hair/dander and bedding materials. Additional downdraft vacuum slots are provided dividing the worktray into quadrants for improved cross-contamination protection from cage to cage during the transfer process. The downdraft HEPA filter provides 99.99% particle removal at 0.3 micron and is located under the worktray in its own impeller/blower/filter cabinet. As the air is pulled from the worktray, through the prefilter and into the blower, the air then passes through the downdraft HEPA filter and is exhausted back to the room providing improved allergen personnel protection. PG 1-10
The exhaust volume is sufficient for proper station function, yet generates low velocities of less than 100 fpm (.51 m/s) at the base of the station minimizing air currents in the room. In comparison, room supply air ducts and personnel traffic can cause draft velocities exceeding 250 fpm (1.27 m/s). The NU-612 performance evaluation was conducted by NuAire to quantify the NU-612's ability to provide product and cross contamination protection as well as improved personnel protection. Product protection was evaluated using two methods: biological testing and particle measurement. Personnel and cross contamination protection was evaluated using biological testing only. 2
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PRODUCT PROTECTION BIOLOGICAL TESTING Procedure The product protection biological testing was performed using a modified NSF Standard 49 testing method for Biological Safety Cabinets (BSC's). A biological challenge of Bacillus subtilis var. niger (B. subtilis) spore suspension at a concentration of no less than 5.0 x 10 6 spores/ml was nebulized outside the station. Two different test setups were used to evaluate product protection in different areas of the station (see Figures 1 & 2). The nebulizer was positioned at 4 inches (102mm) outside the window opening and at a height of 12 inches (305mm) above the worktray. A 2-1/2 inch (63mm) outside diameter cylinder is placed within the center of the test set-up. Seven agar plates were placed on the worksurface in a pyramid shape in the center of the test set-up. A control plate was placed directly under the cylinder and worktray grill. The station was set to nominal airflows for the test. Figure 1 Product Protection Worktray Test Setup #1 Centered in Left Quadrant Figure 2 Product Protection Worktray Test Setup #2 Centered in Workstation 4
The test procedure was to the setup. Turn on the station for 10 minutes. Remove the lids on the agar plates and operate the nebulizer for five minutes. Five minutes after nebulization is terminated, place the lids back on the agar plates and incubate for a minimum of 24 hours at 37 C. Each test setup was run in triplicate. Results A) Test Setup #1 Run #1 Control - 50 B) Test Setup #2 Run #1 Control - 43 Run #2 Control - 23 Run #2 Control - 66 Run #3 Control - 46 Run #3 Control - 47 Conclusion The test results indicate that no contamination is migrating onto the worktray. No Colony Forming Units (CFU's) were recovered on the agar plates. One point to note, normally when this test is conducted, a minimum of 300 CFU's present on the control plates. This would validate that the challenge was sufficient for the test. However, since the nebulizer is positioned at 12 inches above the worktray, most of the airflow at that level is pushing out of the station. Even with this airflow pattern, the challenge was sufficient to pick up countable CFU's. In addition, the nebulizer was weighed before and after the test to validate the correct quantity of spore suspension was nebulized. 5
PRODUCT PROTECTION PARTICLE MEASUREMENT Procedure The product protection particle measurement was performed using a laser particle counter manufactured by Met One, Model Number A2408. The particle counter sample rate was 1 CFM for a particle size of 0.3 micron. Five sampling locations at 2 different height levels were taken within the workzone (see Figure 3). Sampling locations 1 through 4 were positioned 6 inches from the worktray side edge and 4 inches from the worktray front edge. Sampling location 5 was centered in the worktray. The sampling locations were taken in a horizontal plane at window height 14 inches (356mm) and a typical level for a mouse cage at 6-1/2 inches (165mm). Each sampling location was zeroed and particles counted for 1 minute. The total number of particles were then recorded. Figure 3 Particle Measurement Sampling Locations Results A) Test level 14 inches (356mm) above worktray sampling location - particles per cubic foot. B) Test level 6-1/2 inches (165mm) above worktray sampling location - particles per cubic foot. 1-14 3-6 4-12 Conclusion The test results indicate that the workzone cleanliness level is maintained at better than a Class 100 environment throughout the workzone. 6
PERSONNEL PROTECTION BIOLOGICAL TESTING Procedure The personnel protection biological testing was performed using a modified NSF Standard 49 testing method for BSC's. A biological challenge of B. subtilis spore suspension at a concentration of no less than 5.0 x 10 8 spores/ml was nebulized inside the station. Three different test setups were used to evaluate the personnel protection level. The first two test setups used a typical mouse cage centered within the front left worktray quadrant (see Figure 4). The only difference was the first test had the station's hinged windows in their normal down position. The second test had the station's hinged windows in a raised position. The nebulizer was placed inside the mouse cage along with control plate. Several more agar plates were placed around the outside of the mouse cage and in the surrounding quadrants of the worktray. A 2-1/2 inch (63mm) outside diameter cylinder was placed in the center of the worktray extending out of the station. Around the cylinder on the outside of the station, 6 impingers are placed around the cylinder, 2-1/2 inches (63mm) from the station front. Outside the station, two slit samplers are placed 8 inches (203mm) from each end and 6 inches (152mm) from the station front. The test duration is 30 minutes, performed in triplicate, using the following sequence: Time Remaining (min.) Activity 30 start slit samplers 25 start nebulizer 24 start impingers 19 stop impingers 18.5 stop nebulizer 0 stop slit samplers The third test set-up was identical to the first two, except the mouse cage was removed (see Figure 5) Figure 4 Personnel Protection Worktray Test Setup #1 & #2 for both Hinged Windows Closed and Open Test Runs 7
Figure 5 Personnel Protection Worktray Test Setup #3 Results A) Test setup #1 w/hinged windows in normal closed position. Run #1 Run #2 Slits Left-39 Right - 0 Slits Left - 50 Right - 0 Impingers - 20 Impingers - 21 1 > 100 8-0 1 > 100 8-0 2 > 100 9-0 2 > 100 9-0 3 > 100 10-1 3 > 100 10-0 4-4 1 4-4 1 1 1 1 1 1 1 Run #3 Slits Left - 50 Right - 0 Impingers - 33 1 > 100 8-0 2 > 100 9-0 3 > 50 10-0 4-13 1 1 1 1 8
B) Test setup #2 w/hinged window in open position Run #1 Run #2 Slits Left-12 Right - 0 Slits Left -11 Right - 0 Impingers - 1 Impingers - 0 1 - TNTC 8-0 1 - TNTC 8-0 2 - TNTC 9-0 2 - TNTC 9-0 3-2 10-0 3 - TNTC 10-0 4-11 1 4-7 1 1 1 1 1 1 1 Run #3 Slits Left - 2 Right - 0 Impingers - 1 1 - TNTC 8-0 2 - TNTC 9-0 3 - TNTC 10-1 4-8 1 1 1 1 9
C) Test setup #3 w/hinged window in normal closed position. Run #1 Run #2 Slits Left-21 Right - 3 Slits Left - 39 Right - 4 Impingers - 22 Impingers - 27 1 - TNTC 8-0 1 - TNTC 8-0 2-34 9-0 2 - TNTC 9-0 10-0 10-0 1 1 1 1 1 1 1 1 Run #3 Slits Left - 38 Right - 2 Impingers - 43 1 - TNTC 8-0 2 - TNTC 9-0 10-0 1 1 1 1 Conclusion The test results indicate that the downdraft vacuum on the worktray provides both excellent improved allergen protection and cross contamination from quadrant to quadrant. In review of the above data regarding personnel protection, the typical results from the above test runs recorded 20 to 50 CFU's on the Impingers and 25 to 50 CFU's on the slit samplers. In a comparison to the NSF Standard 49 requirements, NSF allows no more than 10 total CFU's on the impingers and no more than 5 total CFU's for the slit samplers. Achieving countable colonies close to the NSF allowable limits with such a large challenge 5.0 x 10 8 B. subtilis spores/ml, indicates that under normal usage, particulates generated in the workzone both in and around the animal cage will most likely be contained. Based upon the above test methods and results, it is our opinion that the NU-612 will provide greater than a 95% allergen personnel protection level. However, again please note, the NU-612 should not be used as a substitute for a Class II, Type A2 BSC. The NU-612 is not a containment device for airborne particulate in low to moderate risk-hazard research. In review of the above data regarding cross-contamination from quadrant to quadrant, only 1 CFU was recorded outside the challenge quadrant on test setup #1, agar plate #10. Based upon the above test methods and results, the NU-612 provides excellent cross-contamination protection from quadrant to quadrant. 10